DE102010060229A1 - Semiconductor device with semiconductor zones and manufacturing method thereof - Google Patents

Abstract

A described embodiment of a semiconductor device comprises first semiconductor zones (105a, 105b) of a first conductivity type which have a first dopant species of the first conductivity type and a second dopant species of a second conductivity type different from the first conductivity type. The semiconductor device also comprises second semiconductor zones (110a, 110b) of the second conductivity type, which have the second dopant species, the first and second semiconductor zones (105a, 105b, 110a, 110b) alternating and adjoining one another along a lateral direction (115) parallel to positioned on a surface of a semiconductor body and wherein a group of first and second semiconductor zones (105a, 105b, 110a, 110b) are drift zones and a diffusion coefficient of the second dopant species is at least twice as large as the diffusion coefficient of the first dopant species. A concentration profile of the first dopant species along a vertical direction (116) perpendicular to the surface of the semiconductor body (100) has at least two maxima.

Description

Semiconductor compensation devices such as n- or p-channel metal-oxide-semiconductor field effect transistors (n- or p-channel MOSFETs), diodes, pn-junction detectors, silicon-controlled rectifiers (SCRs) are widely used in semiconductor products. These devices may be based on mutual charge compensation of n-doped and p-doped regions in a semiconductor body. The n- and p-doped regions are spatially arranged such that a space charge of the n-doped region in a reverse operation mode compensates for the space charge of the p-doped region. By using this compensation of the p- and n-type dopants, a concentration of dopants in the area constituting a drift zone can be increased, so that an improvement in on-resistance R _{DS (on) is} achieved regardless of the possible loss in a current-carrying area can. Manufacturing tolerances such as lithographic offset or deviations in the target dopant concentration can lead to deviations in the desired charge compensation of these n- and p-doped regions. This may have a negative effect on device properties such as a lowered device breakdown voltage and limit the maximum dopant concentration of the n- and p-doped regions.

It is an object of the invention to provide a semiconductor device with semiconductor zones and a manufacturing method thereof, whereby an improved charge carrier compensation can be achieved.

The object is achieved by the teaching of the independent claims. Further developments are the subject of the dependent claims.

1 shows a schematic cross-sectional view of a semiconductor body portion of a semiconductor device according to an embodiment having successive first and second semiconductor regions of different conductivity type.

2 FIG. 12 is a schematic diagram showing a concentration profile of first and second dopant species along that in the cross-sectional view of FIG 1 defined lateral direction AA 'shows.

3 FIG. 12 is a schematic diagram showing a concentration profile of first and second dopant species along that in the cross-sectional view of FIG 1 defined lateral direction BB 'shows.

4A FIG. 12 is a schematic diagram showing a concentration profile of first and second dopant species along that in the cross-sectional view of FIG 1 defined lateral direction CC 'shows.

4B FIG. 12 is a schematic diagram showing a concentration profile of first and second dopant species along that in the cross-sectional view of FIG 1 defined lateral direction CC 'shows.

5A FIG. 12 is a schematic diagram showing a concentration profile of first and second dopant species along a in the cross-sectional view of FIG 1 defined vertical direction DD 'shows.

5B FIG. 12 is a schematic diagram showing a concentration profile of first and second dopant species along that in the cross-sectional view of FIG 1 defined vertical direction DD 'shows.

6A FIG. 12 is a schematic cross-sectional view of a semiconductor body region according to one embodiment of a vertical FET. FIG.

6B FIG. 12 is a schematic plan view of a semiconductor body region according to an embodiment of a lateral FET. FIG.

6C is a schematic cross-sectional view taken along a line AA 'of the in 6B shown lateral FETs.

6D FIG. 12 is a schematic cross-sectional view of a semiconductor body region according to an embodiment of a solar cell. FIG.

7 FIG. 10 is a simplified flowchart of a method of manufacturing a semiconductor device with compensation zones according to one embodiment.

8A FIG. 12 is a schematic cross-sectional view of a semiconductor body region for illustrating a method of manufacturing a semiconductor device according to an embodiment. FIG.

8B FIG. 12 is a schematic cross-sectional view of the semiconductor body region of FIG 8A during implantation of first dopant species and second dopant species.

8C FIG. 12 is a schematic cross-sectional view of the semiconductor body region of FIG 8B after forming a trench in the semiconductor body region.

8D FIG. 12 is a schematic cross-sectional view of the semiconductor body region of FIG 8C after filling the trench with a semiconductor material.

8E FIG. 12 is a schematic cross-sectional view of the semiconductor body region of FIG 8D after diffusion of dopants into the semiconductor material filled in the trenches, around first one Forming semiconductor zones of a first conductivity type and second semiconductor zones of a second conductivity type, which is different from the first conductivity type.

9 FIG. 12 is a schematic cross-sectional view of the semiconductor body region of FIG 8C after forming a barrier diffusion layer and filling the trenches with a semiconductor material.

1 shows a semiconductor body region 100 a semiconductor device having first semiconductor regions 105a . 105b of a first conductivity type and second semiconductor zones 110a . 110b of a second conductivity type different from the first conductivity type. The first and second semiconductor zones are along a lateral direction 115 which extends parallel to an upper side of the semiconductor body, arranged alternately. The sequence of the arrangement of these zones along the lateral direction 115 corresponds to the first semiconductor zone 105a , the second semiconductor zone 110a , the first semiconductor zone 105b and the second semiconductor zone 110b , These zones are positioned in contact with each other.

Each of the first semiconductor zones 105a . 105b includes a first dopant species of the first conductivity type and a second dopant species of the second conductivity type. Because each of the first semiconductor zones 105a . 105b of the first conductivity type, a concentration of a first dopant species within these zones is higher than the concentration of the second dopant species.

Each of the second semiconductor zones 110a . 110b contains the second dopant species. These zones 110a . 110b may also contain the first dopant species in a lower concentration compared to the second dopant species.

One of the first and second semiconductor zones, ie the first semiconductor zones 105a . 105b or the second semiconductor zones 110a . 110b , Drift zones of the device represent. A diffusion coefficient of the second dopant species is at least twice as large as the diffusion coefficient of the first dopant species.

This in 1 shown and the semiconductor body region 100 comprehensive component may include other structural elements that are not in 1 are shown, for example, because these elements in one of the in 1 shown area different component area are positioned or because these elements are not shown for clarity. Examples of these in 1 Elements not shown depend on the type of device and may include, for example, one or a plurality of edge termination structures, measures to increase avalanche robustness, semiconductor structures including body and source, drain, anode, cathode, gate structures including gate dielectrics and gate electrodes, dielectrics, conductive structures such as contact plugs and metal layers.

The first conductivity type may be an n-type and the second conductivity type may be a p-type. As another example, the first conductivity type may be the p-type and the second conductivity type may be the n-type.

The first and second semiconductor zones 105a . 105b . 110a . 110b In a reverse operation mode of the device, a total space charge of at least one of the first semiconductor zones may electrically compensate for the space charge of at least one of the second semiconductor zones. An electrically active dose of at least one of the first semiconductor zones may also be 20% or 10% or even 5% smaller than the corresponding dose of one of the second semiconductor zones, the dose being determined by ∫dN / dx in the first or second semiconductor zones along a lateral one Direction x as the lateral direction 115 and N represents the effective concentration of n-type or p-type charge carriers.

Materials for the first and second dopant species include P and In, Ga and P, B and Sb, In and Sb, Ga and Sb, B and As, In and As, Ga and As. For example, if P and In are combined, the n-type species, ie P, diffuses faster in silicon than In. Thus, a drift zone with a dopant species can be achieved. This can lead to a higher mobility of free charge carriers in the n-type drift zone and to a lower R _{DS (on)} . The diffusion coefficients of the combinations of first and second dopant species with respect to the base material, such as silicon, may differ from one another by at least a factor of two. Thus, forming the first and second semiconductor regions 105a . 105b . 110a . 110b can be achieved with different conductivity type by exploiting the different diffusion properties of these dopants within the semiconductor body. For example, the conductivity type of an originally intrinsic volume after diffusion of the first and second dopant species into the intrinsic semiconductor volume may be determined by the conductivity type of the dopant species having the higher diffusion coefficient, whereas the conductivity type of the semiconductor volume from which these dopant species are diffused is by the conductivity type the other dopant species can be fixed with the lower diffusion coefficient.

A group of the first and the second semiconductor zones 105a . 105b . 110a . 110b For example, at least one may be on a semiconductor substrate along a vertical direction 116 perpendicular to the lateral direction 115 having grown epitaxial semiconductor layer. The other group from the first two semiconductor zones 105a . 105b . 110a . 110b can be within in the semiconductor body 100 be arranged trained trenches. These zones may include epitaxial semiconductor layers disposed on sidewalls of the trenches along the lateral direction 115 have grown up.

The first and / or second dopant species may be implanted in the semiconductor body. This allows an advantageous precision of the charge compensation between the first and second semiconductor zones 105a . 105b . 110a . 110b achieve. The first and / or second dopant species may be implanted using a plurality of implantation doses and / or a plurality of implantation energies. If a group of first and second semiconductor zones 105a . 105b . 110a . 110b may be implanted from a plurality of epitaxial semiconductor layers grown on a semiconductor substrate, one or both of the first and second dopant species may be implanted after forming the respective epitaxial semiconductor layers. For example, one of the first and second dopant species, e.g. B. the one with the larger diffusion coefficient, only in some, z. B. every second or every third of the successively grown epitaxial semiconductor layers are implanted. An implantation dose of the first and / or second dopant species may be chosen to be larger for the top and / or bottom of the plurality of epitaxial semiconductor layers than for the other of these layers, eg. For example, the implantation dose of the faster diffusing dopant species for the top and / or bottom layer can be made higher. As a result, the diffusion of the first and / or second dopant species along a vertical direction through a bottom or top side of the layer stack can be compensated. The implantation doses of the first and second dopant species used for implantation into the plurality of epitaxial layers may be selected so that in the finished device an electrically active dose of at least one of the first semiconductor zones is 20% or 10% or even 5% smaller than that corresponding dose of one of the second semiconductor zones.

Apart from the in 1 shown semiconductor body region 100 For example, the semiconductor body may include a semiconductor substrate such as a silicon substrate or a silicon on insulator (SOI) substrate. The semiconductor substrate may also have one or a plurality of semiconductor layers formed thereon such as epitaxial semiconductor layers. The semiconductor body region 100 may also be part of a doped semiconductor wafer, for. A doped float zone (FZ) or Czochralski (CZ) silicon crystal material.

2 FIG. 12 shows a schematic diagram of an exemplary concentration profile of first and second dopant species C1, C2 along the in. FIG 1 defined lateral direction A-A '.

A concentration C1 of the first dopant species of the first conductivity type is in the first semiconductor region 105a (ie in the left part of the in 2 shown) greater than the concentration C2 of the second dopant species of the second conductivity type. In contrast, the concentration C2 of the second dopant species is within the second semiconductor region 110a (ie in the right part of the in 2 shown) greater than the concentration C1 of the first dopant species within this zone. Thus, the conductivity type corresponds to the first semiconductor region 105a the conductivity type of the first dopant species and the conductivity type of the second semiconductor region 110a corresponds to the conductivity type of the second dopant species.

In other words, a dopant concentration of the first and second species increases at an interface between one of the first semiconductor regions 105a . 105b and one of the second semiconductor zones 110a . 110b along the lateral direction from the first to the second semiconductor zones. The dopant profiles intersect at the interface, wherein a gradient of the profile for the first dopant species is greater than for the second dopant species.

3 FIG. 12 shows a schematic diagram of an exemplary profile of the concentration C1, C2 of first and second dopant species along the in. FIG 1 defined lateral direction B-B '.

A concentration C1 of the first dopant species is within the first semiconductor region 105b (ie right part of in 3 shown) greater than the concentration C2 of the second dopant species. In contrast, the concentration C2 of the second dopant species is within the second semiconductor region 110a (ie left part of in 3 shown) greater than the concentration C1 of the first dopant species. Thus, one conductivity type corresponds to the first semiconductor region 105b the conductivity type of the first dopant species and the conductivity type of the second semiconductor region 110a corresponds to the conductivity type of the second dopant species.

4A shows an exemplary concentration profile C1, C2 of the first and second Dotierstoffspezies along the lateral direction CC 'of in 1 shown semiconductor body region 100 ,

An interface between the profile of the concentration C1 of the first dopant species and the profile of the concentration C2 of the second dopant species defines an interface between a first semiconductor zone such as the semiconductor zone 105a having a concentration of first dopant species C1 greater than the concentration C2 of the second dopant species and a second semiconductor region, such as the semiconductor region 110a which has a concentration C2 of second dopant species which is greater than the concentration C1 of the first dopant species. A schematic profile of concentrations C1, C2, such as in 4A can be generated by first and second dopant species from a volume of the first semiconductor zones, such as the semiconductor zones 105a . 105b in a volume of the second semiconductor zone as the second semiconductor zone 110a , which may be undoped at first, are diffused.

In the in 4A As shown, a diffusion coefficient of the second dopant species is at least twice as large as the diffusion coefficient of the first dopant species. A maximum of the concentration of the dopants C1, C2 of each of the first and second dopant species along the lateral direction CC 'is in the middle of the respective semiconductor regions 105a . 105b and has a same lateral distance to the adjacent second semiconductor zones. A minimum of the concentration C2 of the second dopant species is in the middle of each of the second semiconductor regions, such as the second semiconductor region 110a and has a same lateral distance to the adjacent first semiconductor zones as the first semiconductor zones 105a . 105b on.

In the in 4A example shown remains an area 115 that is free of first dopant species within each of the second semiconductor regions, such as the second semiconductor region 110a , A ripple of each of the profiles of concentrations C1, C2 may depend on a variety of parameters such as the dimensions and distances of the diffusion reservoir regions, the diffusion coefficients of the respective dopant species, the thermal budget, and the diffusion time of the species of interest.

This in 4B The schematic diagram shown illustrates another example of a concentration profile C1, C2 along the lateral direction CC 'of the in 1 shown semiconductor body region 100 a component. With regard to the position of the maxima and minima, the profile of the concentration C2 of the second dopant species is similar to that in FIG 4A shown example.

The profile of the concentration C1 of the first dopant species differs from that in FIG 4A shown profile in that the first dopant species in the entire volume of the second semiconductor zones as the second semiconductor zone 110a is present. Thus, diffusion of the first dopant species from adjacent diffusion reservoirs, such as within the first semiconductor regions, occurs 105a . 105b existing reservoirs such that the two diffusion profiles overlap and no semiconductor volume 115 , which is free of the first dopant species, within the second semiconductor regions such as in FIG 4A shown semiconductor zone 110a remains.

5A shows exemplary concentration profiles C1, C2 of first and second dopant species along a vertical direction DD 'of the first semiconductor zone 105a in the semiconductor body region 100 of in 1 shown component.

Both the concentration profile C1 of the first dopant species and the profile C2 of the second dopant species include maxima and minima along the vertical direction D-D '. The concentration C1 of the first dopant species is greater than the concentration C2 of the second dopant species. Thus, one conductivity type corresponds to this semiconductor region 105a the conductivity type of the first dopant species.

The number of maxima of the concentration profiles C1, C2 along the vertical direction D-D 'may correspond to the number of epitaxial semiconductor layers formed on a semiconductor substrate. The first and second dopant species may be implanted in each of the epitaxial semiconductor layers. Any implantation in one of the epitaxial semiconductor layers may, for example, take place after the formation of the corresponding epitaxial semiconductor layer and before the formation of the subsequent epitaxial semiconductor layer (s). An implantation dose of the first species may correspond to the implantation dose of the second dopant species. These doses may approximate each other and differ by less than 20% or 10% or 5% or 3% or 1% for at least one of the epitaxial semiconductor layers. For example, a fabrication tolerance with respect to the breakdown voltage of the finished device may be set by adjusting the implantation doses of the first and second dopant species to different values, e.g. To the values of the above embodiments. The maxima in the concentration profile C1, C2 of the first and second dopant species may be shifted along the vertical direction D-D 'relative to one another, depending on the implantation energies selected for the implantation of the first and second dopant species.

Linked to the exemplary concentration profile C1, C2, which in 5A is a concentration profile C1, C2 of first and second dopant species along the vertical direction EE 'in FIG 1 shown semiconductor body region 100 , This profile may also have maxima and minima along the vertical direction EE '. In contrast to the relationship C1> C2, which for the profiles along the vertical direction DD 'in 5A is valid, C2> C1 may be valid for the profiles along the vertical direction EE '(not shown).

5B shows another exemplary concentration profile C1, C2 along the vertical direction DD 'in the first semiconductor zone 105a of in 1 shown semiconductor body region 100 ,

In contrast to the example of in 5A The profile shown has the concentration profile C2 of the second dopant species with the larger diffusion coefficient less maxima along the vertical direction DD 'than the concentration profile C1 of the first dopant species. This can be achieved by using multiple implantation energies in implanting the second dopant species and / or, if the first semiconductor zones 105a . 105b in the form of a plurality of epitaxial semiconductor layers, by implanting the second dopant species in fewer of these layers compared to the implantation of the first dopant species. One or both of these profiles may also vary slightly along the vertical direction DD ', e.g. By about 5% or 10% or 20%. Such deviations can serve to improve the avalanche robustness of the component or else to improve the manufacturing tolerance with regard to the breakdown voltage of the component. For example, a concentration of the dopant forming the drift zone may have a peak along the vertical direction DD 'greater than the values at the other maxima, e.g. In a center of the drift zone along the vertical direction D-D '. This example may help to improve the avalanche robustness of the device. As another example, a concentration of the dopant forming the drift zone may have a peak at or near the top and / or bottom of the drift zone, the peak being greater than the values of the further maxima in the vertical direction. This further example may serve to compensate for the vertical diffusion of dopants from the drift zones to be formed.

Linked to the exemplary concentration profiles C1, C2 in 5B are concentration profiles C1, C2 of first and second dopant species along the vertical direction EE 'in the semiconductor body region 100 from 1 , In contrast to the relationship C1> C2, which applies to the profiles along the vertical direction DD ', C2> C1 may be valid for the profiles along the vertical direction EE' (not shown).

Further exemplary dopant concentrations C1, C2 along the vertical direction D-D 'may comprise parts with maxima and minima as well as further parts with constant dopant concentration. Such profiles can be produced, for example, by a combination of an in-situ doping and a doping via implantation of dopants.

6A shows a schematic cross-sectional view of a portion of a vertical FETs 201 , the n-type semiconductor zones 205a . 205b and a p-type semiconductor region 210a having. These semiconductor zones are along the lateral direction 215 consecutively in the order of first semiconductor zone 205a , second semiconductor zone 210a and first semiconductor zone 205b arranged. The profile of the concentration of the first and second dopant species within these semiconductor regions may coincide with any of the exemplary profiles described above. The first semiconductor zones 205a . 205b make drift zones of the FET 201 In a reverse operating mode of the FET 201 Free charge carriers can be removed from these areas and achieve a charge compensation between the first and second semiconductor zones, ie the space charge of one of the first zones can electrically compensate for the space charge of one of the second zones.

The FET 201 contains a semiconductor structure 225 with a p-type body area 226 and an n ⁺ type source region 227 , which at a front 230 a semiconductor body region 200 are formed.

An n ⁺ -type drain 235 is at a backside of the semiconductor body region 200 opposite the front 230 educated. An n-type semiconductor zone 240 can be between the first and second semiconductor zones 205a . 205b . 210a and the n ⁺ -type drain 235 trained one. The n-type semiconductor zone 240 may have a dopant concentration which is the dopant concentration of the first semiconductor zone 205a equivalent. As another example, a dopant concentration of the semiconductor region 240 greater or smaller than the concentration of the first semiconductor zones 205a . 205b , The semiconductor zone 240 may be a field stop zone that improves the robustness such as the avalanche robustness of the FET 201 by compensation of free electrons, which flow as leakage current approximately in the reverse state, is suitable.

On the front side 230 is a conductive structure 245 electrically with the semiconductor structure 225 coupled. The conductive structure 245 can be conductive Elements such as contact plugs and conductive layers of conductive materials such as metals and / or doped semiconductors include. The conductive structure 245 is suitable for an electrical connection between the component 201 and other elements such as circuit elements or chip pads.

The FET 201 also contains gate structures 250a . 250b , the gate dielectrics 252a . 252b , Gate electrodes 254a . 254b and insulating layers 256a . 256b include.

6B shows a schematic plan view of a portion of a lateral FETs 301 with n-type semiconductor zones 305a ... 305c and p-type semiconductor zones 310a ... 310c , These semiconductor zones are along a lateral direction 315 consecutively in the sequence first semiconductor zone 305a , second semiconductor zone 310a , first semiconductor zone 305b , second semiconductor zone 310b , first semiconductor zone 305c and second semiconductor zone 310c arranged. The profile of the concentrations of the first and second dopant species within these semiconductor zones may coincide with any profiles from the above examples. The first semiconductor zones 305a ... 305c make drift zones of the FET 301 In a reverse operating mode of the FET 301 Free charge carriers can be removed from these areas and achieve charge compensation of the first and second semiconductor zones, ie, the space charge of one of the first zones can electrically compensate for the space charge of one of the second zones.

The FET 301 also contains an n ⁺ -type drain 335 and a p-type body area 326 , The first and second semiconductor zones 305a ... 305c . 310a ... 310c are between the n ⁺ -type drain 335 and the p-type body area 326 along the lateral direction 316 arranged. An n ⁺ type source area 327 is within the p-type body area 326 embedded and a gate structure 350 is provided to control the conductivity in a channel region between the n ⁺ -type source region 327 and control the drift zones by field effect. The FET 301 may also include additional elements such as semiconductor regions, which are not shown for reasons of clarity.

6C shows a cross-sectional view of the in 6B shown FETs 301 on the line A-A '. The first and second semiconductor zones as the first semiconductor zone 305c which forms part of the drift zone, the n ⁺ -type drain 335 , the p-type body area 326 and the n ⁺ -type source region 327 are within an n-type semiconductor body region 300 educated. The gate structure 350 that is a gate dielectric 352 and a gate electrode 354 includes is on the p-type body area 326 educated. The gate structure 350 is provided to control the conductivity of a lateral channel region 360 between the n ⁺ type source region 327 and the drift zones as the first semiconductor zone 305c to control by field effect. The FET 301 may also include additional elements such as semiconductor regions or contact plugs, which are not shown for clarity.

6D shows a schematic cross-sectional view of a semiconductor body region 400 a solar cell 401 or a radiation detector with p-type semiconductor zones 405a ... 405e and n-type semiconductor zones 410a ... 410d , These semiconductor zones are along a lateral direction 415 arranged consecutively. The profile of the concentrations of the first and second dopant species within these semiconductor regions may correspond to any of the exemplary profiles described above. The electrically active dose of the vertical p- and n-type regions may differ more than compensation components, the difference being about a factor of 10 or 5 or 2 or 50% or 20%. The first semiconductor zones 405a ... 405e create base zones (drift zones) of a solar cell 401 and the second semiconductor zones 410a ... 410d represent comparatively low-doped emitter zones of the solar cell 401 dar. A highly doped n ⁺ -type emitter 470 is at a front 430 of the semiconductor body region 400 formed and a p ⁺ -type base contact area 471 is at a back 431 of the semiconductor body region 400 educated. A lateral distance d between two adjacent ones of the first semiconductor zones 405a ... 405e may be within a range of a few tenths of the electron diffusion length to a plurality of electron diffusion lengths within the first semiconductor regions 405a ... 405e be.

7 shows a simplified flowchart of a method for manufacturing a semiconductor device according to an embodiment.

At S100, first semiconductor regions of a first conductivity type are formed, wherein the first semiconductor regions have a first dopant species of the first conductivity type and a second dopant species of a second conductivity type different from the first conductivity type.

At S200, second semiconductor regions of the second conductivity type are formed, wherein the second semiconductor regions contain the second dopant species. The first and second semiconductor zones are arranged alternately and in contact with each other along a lateral direction extending parallel to a surface of a semiconductor body, wherein a group of first and second semiconductor zones represents drift zones and a diffusion coefficient of the second dopant species is at least twice as large Diffusion coefficient of the first dopant species is selected. Forming the first and second semiconductor regions may be made common, and forming the first semiconductor regions comprises forming a concentration profile of the first dopant species along a vertical direction perpendicular to the surface of the semiconductor body by ion implantation to include at least two maxima.

The schematic cross-sectional views of 8A to 8E show an exemplary method for manufacturing a semiconductor device with semiconductor compensation zones.

In the schematic cross-sectional view of 8A is a semiconductor substrate 850 with an epitaxial layer formed thereon 855 shown. A thickness of the epitaxial layer 855 may for example be in a range of 3 microns to 15 microns.

In the schematic cross-sectional view of 8B For example, a first dopant species of a first conductivity type and a second dopant species of a second conductivity type other than the first conductivity type are introduced into the epitaxial layer 855 implanted. Materials of the first and second dopant species include P and In, Ga and P, B and Sb, In and Sb, Ga and Sb, B and As, In and As, Ga and As. The materials of the first and second dopant species may be selected such that their diffusion coefficient with respect to the base material, e.g. As silicon, differs by at least a factor of 2. Thus, with respect to silicon as the base material, approximately B and P are not suitable materials for the first and second dopant species.

The dopant species may enter the epitaxial layer 855 implanted with one or more implantation doses and with one or more implantation energies. The process of forming the epitaxial layer 855 and implanting dopants into the epitaxial layer 855 may be repeated to form a plurality of doped epitaxial semiconductor layers on the semiconductor substrate 850 train. In this way, a thickness of the drift zone can increase to within a range of 10 microns to several 100 microns. The doping of some of the epitaxial layers 855 with one species or both species of first and second dopant species may also be done in-situ, ie, during production of the epitaxial layer 855 , In this case, the thickness of the epitaxial semiconductor layer may be within a range of 10 μm to several 100 μm. If a plurality of epitaxial semiconductor layers are formed, any combination of undoped, ie, intrinsic epitaxial, in-situ doped epitaxial layers and epitaxial layer doped dopant species may be combined as long as the final layer stack forming the drift zone comprises the first dopant species and the second dopant species, and at least a portion of these layers are doped by implantation of dopant species. A total amount of the first dopant species may correspond to the total amount of the second dopant species. As a result, a precise charge compensation between the first and second semiconductor zones can be achieved by defining these zones on the basis of different diffusion profiles of the first and second dopant species. An implantation dose of the first dopant species may correspond to the implantation dose of the second dopant species. These doses may also approximate and differ by less than 20% or 10% or 5% or 3% or 1% with respect to at least one of these epitaxial layers. For example, a manufacturing tolerance with respect to the breakdown voltage of the resulting device may be set by setting the implantation dose of the first and second dopant species to different values, e.g. For example, the values of the above embodiments can be improved.

As another example, a semiconductor substrate containing the first and second dopant species is used. Thus, the process of implanting dopants is as in 8B shown, not required. A total amount of the first dopant species may correspond to the total amount of the second dopant species. The manufacturing process can with the in 8C to 8E processes are continued. An example of a doped semiconductor substrate is a semiconductor wafer doped with the first and second dopant species, e.g. Doped float zone (FZ) or Czochralski (CZ) or magnetic Czochralski (MCZ) silicon crystal material. When the manufacturing process for manufacturing solar cells or detectors is used, for example, doped semiconductor wafers can be used. In the case of solar cells and radiation detectors, charge carriers generated by light absorption diffuse a certain distance to arrive at a charge-separating junction such as a pn junction. If this distance is shorter than the diffusion length of the minority carriers, these carriers can contribute to the photocurrent and increase the quantum efficiency. The above structure with the first and second semiconductor zones may be advantageous for such devices with vertical pn junctions. For example, a lateral distance between two adjacent first and / or second semiconductor zones may be within a range of a few tenths of the minority carrier diffusion length to a plurality of minority carrier diffusion lengths of the corresponding first and / or second semiconductor zones.

Thermal heating may be used to diffuse the implanted dopant species. Thereby, the distribution of the implanted dopant species can be flattened along a vertical direction perpendicular to a front side. Before the thermal heating, a cap layer such as an SiO ₂ layer may be formed to cover the front side. This cover layer, which prevents outdiffusion of the implanted dopant species during thermal heating, may be removed in a later process. Prior to thermal heating, a vertical concentration profile such as a vertical implant profile of the dopant species of first and second dopant species having more diffusion may have an absolute maximum at a back side and / or the front side as well as one or more local maxima between the front side and the front side Back. This can counteract increased diffusion from the silicon wafer into the substrate with respect to the faster diffusing dopant species.

In the schematic cross-sectional view of 8C becomes a ditch 860 within the epitaxial layer 855 educated. The ditch 860 can be formed for example by an etching process. In the in 8C The example shown is a bottom of the trench 860 above an upper surface of the semiconductor substrate 850 positioned. As another example, the trench may become 860 in the semiconductor substrate 850 extend or even at an interface between the epitaxial layer 855 and the semiconductor substrate 850 end up.

In the schematic cross-sectional view of 8D becomes the trench with a filler 865 filled, which comprises at least one semiconductor material. For example, the trench 860 are filled by lateral epitaxy, ie by forming epitaxial layers on sidewalls of the trench 860 , The epitaxial layers may be formed as intrinsic layers such as intrinsic Si layers. As another example, the epitaxial layers may be doped in-situ. In the latter case, a dopant concentration within the in-situ doped epitaxial layers may be smaller than the concentration of the first and second dopant species. After filling the trench 860 For example, a planarization and / or formation of a cover layer such as a SiO ₂ layer on the front side can take place.

In the schematic cross-sectional view of 8E For example, the first and second dopant species are heated by thermal treatment such as heating into a volume of the filled trench 860 diffused. Due to the different diffusion coefficients of the first and second dopant species, which have a different conductivity type, first zones become 805a . 805b and a second zone 810 of different conductivity type, because the species with the larger diffusion coefficient is the conductivity type within the volume of the filled trench 860 certainly. Assuming that the diffusion coefficient of the second dopant species is at least twice as large as the diffusion coefficient of the first dopant species, one conductivity type corresponds to the first zones 805a . 805b the conductivity type of the first dopant species and the conductivity type of the second zone 810 corresponds to the conductivity type of the second dopant species. Examples of profiles of the first and second dopant species along a lateral and vertical direction within the first and second semiconductor regions can be found in the above 1 to 5B ,

Due to the different diffusion coefficients of the first and second dopant species, a semiconductor structure having a sequence of p-type and n-type semiconductor regions such as stripes or columns can be formed. Regardless of the thermal budget employed, advantageous charge compensation of these n- and p-type regions can be achieved since the one species of first and second dopant species having the larger diffusion coefficient partially dopes the other species with the lower diffusion coefficient in a first region , whose conductivity is defined by the other species, compensates, whereas the one dopant species determines the conductivity type and dimensions in a second region adjacent to the first region. This means that the state of charge compensation that existed before the etch and before the lateral outdiffusion in the filled trench remains approximately unchanged since the faster diffusing dopant species remaining in the first region partially compensates for the slower diffusing dopant species, so that it Difference, which is equal to the electrically active dopant dose in the first region, the difference amount of the faster and slower diffusing Dotierstoffspezies and consequently the electrically active dose in the second region corresponds.

A value of the resulting dopant concentration in the regions defining the current path areas during operation, such as the drift regions, may be determined by the dimensions, such as width and shape of the first regions, and dimensions such as width and shape of the second regions, implantation doses and type of dopant species, temperature and duration the diffusion processes for the first and second dopant species are determined. Prior to diffusion of the first and second dopant species, the second regions may be formed as intrinsic regions within the trenches. Thus, compensation zones with higher dopant levels can be achieved compared to compensation zones of existing elements, such as dopant levels of more than 10 ¹⁶ cm ^-3 , more than a few 10 ¹⁶ cm ^-3 or even more 10 ¹⁷ cm ^-3 .

In addition, a vertical variation in dopant levels may be kept smaller than in existing comparable devices, and the vertical pn junctions may have negligible curvature, allowing for low R _on values for a given breakdown voltage of the device. The vertical variations in dopant levels can be kept substantially smaller than in existing comparable devices, provided that the difference in the 5A maxima and minima are minimized by a suitable selection of high-temperature processes. The manufacturing costs of the proposed devices can be kept low, since a single lithography process for producing a drift zone with a charge compensation structure can be sufficient. In addition, the degree of charge compensation is independent of lithographic offset.

Other processes such as body, source, and drain formation, as well as controlled thinning of a substrate, such as a wafer, may be followed from a backside to complete the desired semiconductor device. Examples of a semiconductor device fabricated by the above method include MOSFETs, Insulated Gate Bipolar Transistors (IGBTs), SCRs, diodes, solar cells and pn-junction radiation detectors.

The first and / or second semiconductor zones forming the compensation structure can be strip-shaped, columnar, annular, hexagonal, octagonal, or else consist of their complementary structures. When strips are used for the shape of the compensation structure, a width of the trenches may be a distance between the trenches within a range of 100 nm to 10 μm, or between 200 nm and 3 μm.

In the region of an edge termination of the device, a spacing and / or a width of the trenches may be varied in order to lower the effective dopant concentration in this region, e.g. By increasing the width or by skipping some of these trenches. Additionally or alternatively, conventional edge termination structures such as field plates and / or field rings can be used.

In the schematic cross-sectional view of 9 is related to the 8A - 8E shows another example of manufacturing a semiconductor device. This procedure differs from that in the 8A to 8E shown method by the additional formation of a diffusion barrier 970 within the trench 960 and along the sidewalls of the trench, prior to filling the trench 960 with a filling material 965 , A material of the diffusion barrier 970 can be chosen such that it allows the diffusion of one of the first and second dopant species from the first zones 905a . 905b in the second zones 910 prevents. For example, a diffusion barrier with layers of SiO ₂ and Si ₃ N ₄ hinders the diffusion of P as the first dopant species. As a second dopant species whose diffusion is not hindered by the diffusion barrier, Ga may be chosen, for example.

Claims (25)

A semiconductor device comprising: first semiconductor regions ( 105a . 105b ) of a first conductivity type having a first dopant species of the first conductivity type and a second dopant species of a second conductivity type different from the first conductivity type; second semiconductor zones ( 110a . 110b ) of the second conductivity type having the second dopant species, the first and second semiconductor regions alternately and adjacent to each other along a lateral direction (FIG. 115 ) parallel to a surface of a semiconductor body ( 100 ) are positioned; where a group of the first ( 105a . 105b ) and second ( 110a . 110b ) Are semiconductor zones drift zones and a diffusion coefficient of the second dopant species is at least twice as large as the diffusion coefficient of the first dopant species; and a concentration profile of the first dopant species along a vertical direction ( 116 ) perpendicular to the surface of the semiconductor body ( 100 ) has at least two maxima. The semiconductor device of claim 1, wherein the first ( 205a . 205b ) and second ( 210a ) Semiconductor zones between a body ( 226 ) and a source ( 227 ) semiconductor structure ( 225 ) on a first surface of the semiconductor body ( 200 ) and a drain ( 235 ) on a first surface opposite the second surface of the semiconductor body ( 200 ) are arranged. The semiconductor device according to claim 2, additionally comprising a semiconductor region ( 240 ), which is between the drain ( 235 ) and each of the first ( 205a . 205b ) and second ( 210a ) Semiconductor regions, wherein the conductivity type of the semiconductor region ( 240 ) the conductivity type of the drain ( 235 ) corresponds. The semiconductor device according to one of the preceding claims, wherein a maximum of Concentration profile of dopants of each of the first and second dopant species along the lateral direction ( 115 ) in the middle of the first semiconductor zones ( 105a . 105b ) and a same lateral distance to the adjacent second semiconductor zones ( 110a . 110b ) having. The semiconductor device according to one of the preceding claims, wherein a concentration profile of the dopants of the respective first and second species at a transition between the first ( 105a . 105b ) and second ( 110a . 110b ) Semiconductor zones along the lateral direction ( 115 ) decreases from the first to the second semiconductor regions. The semiconductor device according to one of the preceding claims, wherein the first ( 105a . 105b ) Semiconductor zones and the second ( 110a . 110b ) Semiconductor zones compensate each other by at least 80% electrically. The semiconductor device according to any one of the preceding claims, wherein materials for the first and second dopant species are selected from P and In, Ga and P, B and Sb, In and Sb, Ga and Sb, B and As, In and As, or Ga and As. The semiconductor device according to one of the preceding claims, wherein the one group of the first ( 105a . 105b ) and second ( 110a . 110b ) Semiconductor zones comprises at least one epitaxial semiconductor layer on a semiconductor substrate. The semiconductor device of claim 5, wherein each zone is from the other group of the first ( 105a . 105b ) and second ( 110a . 110b ) Semiconductor zones within a trench ( 860 ) and the trench ( 860 ) is formed within the semiconductor body. The semiconductor device of claim 6, wherein the inside of the trenches ( 860 ) ( 810 ) comprise epitaxial semiconductor layers which are provided on sidewalls of the trenches ( 860 ) are formed, wherein the epitaxial semiconductor layers are in contact with each other. The semiconductor device according to one of the preceding claims, wherein a number of maxima in the concentration profile of the first dopant species along the vertical direction (FIG. 116 ) perpendicular to the surface of the semiconductor body ( 100 ) of the number of maxima in the concentration profile of the second dopant species along the vertical direction ( 116 ) corresponds. The semiconductor device according to any one of claims 1 to 11, wherein a number of maxima in the concentration profile of the first dopant species along the vertical direction (FIG. 116 ) perpendicular to the surface of the semiconductor body ( 100 ) is greater than the number of maxima in the concentration profile of the second dopant species along the vertical direction ( 116 ). A method of manufacturing a semiconductor device, comprising: forming first semiconductor regions ( 805a . 805b ) of a first conductivity type having a first dopant species of the first conductivity type and a second dopant species of a second conductivity type different from the first conductivity type; Forming second semiconductor zones ( 810 ) of the second conductivity type having the second dopant species, the first and second semiconductor regions alternately and adjacent to each other along a lateral direction (FIG. 115 ) are positioned parallel to a surface of a semiconductor body; where a group of the first ( 805a . 805b ) and second ( 810 ) Are semiconductor zones drift zones and a diffusion coefficient of the second dopant species is at least twice as large as the diffusion coefficient of the first dopant species; and forming the first semiconductor regions ( 805a . 805b ) comprises forming a concentration profile of the first dopant species along a vertical direction perpendicular to the surface of the semiconductor body by means of ion implantation such that the concentration profile has at least two maxima. The method of claim 13, wherein forming the first ( 805a . 805b ) and second ( 810 ) Semiconductor zones comprises: forming at least one epitaxial semiconductor layer ( 855 ) on a semiconductor substrate ( 850 ); Implanting the first dopant species into the at least one epitaxial semiconductor layer ( 855 ) using at least two different implantation energies; Forming trenches ( 860 ) in the at least one epitaxial semiconductor layer ( 855 ); Filling the trenches with a filling material ( 865 ) comprising at least one semiconductor material; Heating the at least one epitaxial semiconductor layer ( 855 ) to the second dopant species in the semiconductor material within the trenches ( 860 ) to diffuse. The method of claim 13 or 14, wherein forming the first ( 805a . 805b ) and second ( 810 ) Semiconductor regions comprises implanting the first and second dopant species. The method of claim 15, wherein the implantation of at least one group of the first and second dopant species is performed with multiple implantation energies. The method of claim 15 or 16, wherein the implantation of at least one group of first and second dopant species is performed with multiple implantation doses. The method of any one of claims 15 to 17, wherein a plurality of epitaxial layers are formed and a thickness of each of the plurality of epitaxial layers is set between 3 μm and 15 μm. The method of any one of claims 15 to 18, wherein filling the trenches ( 860 ) with a filling material, forming an epitaxial semiconductor layer on sidewalls of the trenches (US Pat. 860 ). The method according to one of claims 13 to 19, additionally comprising forming a semiconductor structure ( 225 ) with a body ( 226 ) and a source ( 227 ) on a first surface of the semiconductor body ( 200 ); Forming a drain ( 235 ) on a second surface of the semiconductor body ( 200 ) opposite the first surface; and wherein the first and second semiconductor zones between the semiconductor structure ( 225 ) and the drain ( 235 ) are arranged. The method of any one of claims 13 to 20, wherein the first and second dopant species are over an entire surface ( 230 ) of the first ( 205a . 205b ) and second ( 210a ) Semiconductor zones of defined semiconductor body region ( 200 ) are implanted. The method of any of claims 13 to 21, wherein a total implantation dose of the first and second dopant species differ by at least 20% with respect to the semiconductor body. The method of manufacturing a semiconductor device according to claim 13, wherein forming the first and second semiconductor regions comprises: Forming a plurality of epitaxial semiconductor layers on a semiconductor substrate, wherein after forming at least two of the plurality of epitaxial semiconductor layers, first dopant species are implanted in the corresponding epitaxial layer; Forming trenches in the at least one epitaxial semiconductor layer; Filling the trenches with a filler material comprising at least one semiconductor material; and Heating the plurality of epitaxial semiconductor layers to diffuse the second dopant species into the semiconductor material within the trenches. The method of claim 23, further comprising forming an oxide layer on a surface of the semiconductor body prior to heating the plurality of epitaxial semiconductor layers, wherein the oxide layer remains during heating of the plurality of epitaxial semiconductor layers. An integrated circuit comprising the semiconductor device according to one of the preceding claims, wherein the semiconductor device is an element of FET, IGBT, solar cell, pn-junction detector.

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